Electrical fuse and/or resistor structures

ABSTRACT

Electrical fuse (eFuse) and resistor structures and methods of manufacture are provided. The method includes forming metal gates having a capping material on a top surface thereof. The method further includes protecting the metal gates and the capping material during an etching process which forms a recess in a dielectric material. The method further includes forming an insulator material and metal material within the recess. The method further includes forming a contact in direct electrical contact with the metal material.

FIELD OF THE INVENTION

The invention relates to semiconductor structures and, moreparticularly, to electrical fuse (eFuse) and resistor structures andmethods of manufacture.

BACKGROUND

Electrical fuses (eFuses)/metal resistors are essential forsemiconductor applications such as system-on-chips (SoCs). However,conventional poly fuses/resistors are not feasible due toincompatibility with gate-last high-k/metal gate technology withself-aligned contacts. For example, in the process flow of forming theeFuses/metal resistors, nitride material formed on the top of metal gatematerial becomes damaged during the etching processes with selectivechemistries.

SUMMARY

In an aspect of the invention, a method comprises: forming metal gateshaving a capping material on a top surface thereof; protecting the metalgates and the capping material during an etching process which forms arecess in a dielectric material; forming an insulator material and metalmaterial within the recess; and forming a contact in direct electricalcontact with the metal material.

In an aspect of the invention, a method comprises: forming metal gatestructures in a dielectric material; forming a capping material over themetal gate structures; forming a mask over the capping material of themetal gate structures; recessing the dielectric material between themetal gate structures by an etching process while the mask over thecapping material protects the capping material and the metal gatestructures; depositing insulator material and metal material within therecess in the dielectric material; and forming a contact in directelectrical contact with the metal material.

In an aspect of the invention, a structure comprises: an efuse formedbetween replacement gate metals in a dielectric material, thereplacement gate metals including a nitride capping material, the efuseis provided within a recess of the dielectric material, and the efusecomprises a nitride insulator material and a metal material which is incontact with a contact structure formed in an insulator material abovethe efuse.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIG. 1 shows a starting structure and respective fabrication processesaccording to aspects of the present invention.

FIG. 2 shows a recessed portion in a dielectric material and respectivefabrication processes according to aspects of the present invention.

FIG. 3 shows materials in the recessed portion and respectivefabrication processes according to aspects of the present invention.

FIG. 4 shows a planar surface formed from the materials in the recessedportion and respective fabrication processes according to aspects of thepresent invention.

FIG. 5 shows a contact structure contacting a metal material andrespective fabrication processes according to aspects of the presentinvention.

FIG. 6 shows a recessed portion in a dielectric material and respectivefabrication processes according to another aspect of the presentinvention.

FIG. 7 shows materials in the recessed portion and respectivefabrication processes according to the other aspect of the presentinvention.

FIG. 8 shows a planar surface of the materials in the recessed portionand respective fabrication processes according to the other aspect ofthe present invention.

FIG. 9 shows a contact structure in contact with a metal material andrespective fabrication processes according to the other aspect of thepresent invention.

FIG. 10 shows a beginning structure and respective fabrication processesaccording to yet another aspect of the present invention.

FIG. 11 shows contact trenches in a dielectric material between gatestructures and respective fabrication processes according to yet anotheraspect of the present invention.

FIG. 12 shows metal contacts formed in the contact trenches andrespective fabrication processes according to yet another aspect of thepresent invention.

FIG. 13 shows an opening formed in insulator material to expose themetal contacts and respective fabrication processes according to yetanother aspect of the present invention.

FIG. 14 shows materials in the opening of the insulator material andrespective fabrication processes according to yet another aspect of thepresent invention.

FIG. 15 shows contact structures in contact with the metal contacts andrespective fabrication processes according to yet another aspect of thepresent invention.

FIG. 16 shows an alternative structure and respective fabricationprocesses according to still yet another aspect of the presentinvention.

DETAILED DESCRIPTION

The invention relates to semiconductor structures and, moreparticularly, to electrical fuse (eFuse) and resistor structures andmethods of manufacture. More specifically, the present inventionprovides a method and structure for forming electrical fuses/resistorswhich are embedded in middle of the line (MOL) interlevel dielectric(ILD) layers. For example, in embodiments described herein, a thin metallayer between contacts can be used as fuse links/resistors.

In embodiments, electrical contacts to the fuses/resistors arephysically isolated from the fuses, with the electrical connectionachieved through contacts, e.g., tungsten contacts, formed on top of thegate metal. The structures of the present invention also preventdiffusion of copper into the fuses/resistors thus improving reliability.Moreover, the fabrication processes described herein can be used postSAC (semi-aqueous chemistry) cap formation to form replacement metalgate (RMG) and eFuses. In additional embodiments, the methods forfabricating the eFuse and resistor structures are fully compatible withcurrent CMOS integration processes.

The eFuse and resistor structures of the present invention can bemanufactured in a number of ways using a number of different tools. Ingeneral, though, the methodologies and tools are used to form structureswith dimensions in the micrometer and nanometer scale. Themethodologies, i.e., technologies, employed to manufacture the eFuse andresistor structures of the present invention have been adopted fromintegrated circuit (IC) technology. For example, the structures of thepresent invention are built on wafers and are realized in films ofmaterial patterned by photolithographic processes on the top of a wafer.In particular, the fabrication of the eFuse and resistor structures ofthe present invention uses three basic building blocks: (i) depositionof thin films of material on a substrate, (ii) applying a patterned maskon top of the films by photolithographic imaging, and (iii) etching thefilms selectively to the mask.

FIG. 1 shows a structure and respective fabrication processes accordingto aspects of the present invention. In embodiments, the structure 10includes a metal 16 (e.g., gate metal) with spacers and cap material 14formed on sidewalls and a top of the gate metal 16. As should beunderstood by those of skill in the art, the gate metal 16 is formed inthe active region of the structure 10. The gate metal 16 and spacers andcap material 14 are formed in an interlevel dielectric material 12 usingconventional lithography, etching and deposition methods as should beunderstood by those of skill in the art such that further explanation isnot required. In embodiments, the gate metal 16 can be TiN, tungsten orother gate metals known to those of skill in the art. The gate metal 16can also be representative of a dummy or replacement gate metal. Thespacers and cap 14 are preferably nitride material.

As shown in FIG. 2, a recess 20 is formed in the interlevel dielectricmaterial 12, e.g., between adjacent gate metals 16. In embodiments, therecess 20 is formed using lithography and etching processes. Morespecifically, a mask (photoresist) 18 is exposed to energy (light) toform a pattern masking the active region, e.g., gate metal 16. Theinterlevel dielectric material 12 is then subjected to an etchingprocess, e.g., reactive ion etching (using SAC), to remove portions ofthe interlevel dielectric material 12. During this etching process, thegate metal 16 and cap material 14, e.g., nitride, remain protected bythe mask 18 such that the cap material 14 will not be removed or erodedfrom a top of the gate metal 16 during the etching process. In this way,for example, a resistor module will not be affected by erosion caused bythe SAC. In embodiments, the recess 20 can be about 15 nm to 80 nm deep,and more preferably about 35 nm to 40 nm deep.

As shown in FIG. 3, a nitride material 22 is deposited within the recess20, followed by a metal material 24. In embodiments, an oxide materialcan be deposited on the metal material, as also shown by referencenumeral 24. In embodiments, the metal material 24 can be, e.g., WSix;although other metals or metal alloys are also contemplated by thepresent invention. In embodiments, the nitride material 22 and metalmaterial 24 can be deposited using conventional deposition processes,e.g., chemical vapor deposition (CVD) processes. The metal material 24can be used to form an eFuse or resistor in accordance with any of theaspects of the present invention, depending on its thickness. Forexample, the metal material 24 can be deposited to a thickness of about5 nm to 10 nm, and more preferably about 10 nm; although otherdimensions are also contemplated by the present invention.

In FIG. 4, the nitride material 22 and metal material 24 undergo apolishing process to planarize these materials thus forming a planarsurface. In embodiments, the polishing process can be, for example, achemical mechanical polishing process. In this way, the nitride material22 and metal material 24 remain within the recess 20, and any additionalmaterial is removed from the cap material 14. Also, the cap material 14will remain intact above the gate metal 16.

In FIG. 5, a contact structure 28 is formed in direct electrical contactwith the metal material 24. In embodiments, the contact structure 28 isformed through an insulator material 26, e.g., oxide, using conventionallithography, etching and deposition processes. For example, afterdeposition of the insulator material 26, a mask (photoresist) can bedeposited on the insulator material 26 and exposed to energy to form apattern. An etching process, e.g., RIE, can then be performed throughthe pattern to form an opening in the insulator material 26 to exposethe underlying metal material 24. A metal material or alloy thereof,e.g., tungsten, TiN, etc., can then be deposited within the opening toform the contact structure 28. Any residual material formed on theinsulator material 26 can then removed by a CMP process.

FIGS. 6-9 show an alternative structure and respective fabricationprocesses according to additional aspects of the present invention.Referring to FIG. 6, the structure 10′ includes gate modules 14′ and 14″(e.g., dummy gate material) formed in an interlevel dielectric material12 using conventional lithography, etching and deposition methods asshould be understood by those of skill in the art such that furtherexplanation is not required. In embodiments, the gate modules 14′ and14″ can be nitride material, e.g., TiN.

As further shown in FIG. 6, a recess 20 is formed in the interleveldielectric material 12. In embodiments, the recess 20 is formed usinglithography and etching processes. More specifically, a mask(photoresist) is exposed to energy (light) to form a pattern masking theactive region, e.g., gate metal 16. The interlevel dielectric material12 and the gate module 14″ is then subjected to an etching process,e.g., RIE, to remove portions of the interlevel dielectric material 12and the gate module 14″. During this etching process, the gate modules14′, e.g., nitride, remain protected by the mask. In embodiments, therecess 20 can be about 15 nm to 80 nm deep, and more preferably about 35nm to 40 nm deep.

As shown in FIG. 7, a nitride material 22 is deposited within the recess20, followed by a metal material 24 and an insulator material 30, e.g.,nitride material. In embodiments, the metal material 24 can be, e.g.,WSix; although other metals or metal alloys are also contemplated by thepresent invention. In embodiments, the nitride material 22, metalmaterial 24 and insulator material 30 can be deposited usingconventional deposition processes, e.g., chemical vapor deposition (CVD)processes. The metal material 24 can be used to form an eFuse orresistor in accordance with aspects of the present invention, dependingon its thickness. For example, the metal material 24 can be deposited toa thickness of about 5 nm to 10 nm, and more preferably about 10 nm;although other dimensions are also contemplated by the presentinvention.

In FIG. 8, the nitride material 22, metal material 24 and insulatormaterial 30 undergo a polishing process to planarize these materialsthus forming a planar surface. In embodiments, the polishing process canbe, for example, a CMP process. In this way, the nitride material 22,metal material 24 and insulator material 30 remain within the recess 20,and any additional material is removed from the gate modules 14′.

In FIG. 9, a contact structure 34 is formed in direct electrical contactwith the metal material 24. In embodiments, the contact structure 34 isformed through insulator material 26, e.g., oxide, using conventionallithography, etching and deposition processes. For example, afterdeposition of the insulator material 26, a mask (photoresist) can bedeposited on the insulator material 26 and exposed to energy to form apattern. An etching process, e.g., RIE, can then be performed throughthe pattern to form an opening in the insulator material 26 to exposethe underlying metal material 24. A metal material or metal alloy, e.g.,tungsten, TiN, etc., can be deposited within the opening to form thecontact structure 28. Any residual material formed on the insulatormaterial 26 can then removed by a CMP process.

FIGS. 10-15 show an alternative structure and respective fabricationprocesses according to additional aspects of the present invention.Referring to FIG. 10, the structure 10″ includes a post CMP structurehaving a gate structure 100 formed in an interlevel dielectric material120 (formed on an insulator material, e.g., STI or BOX) usingconventional lithography, etching and deposition methods as should beunderstood by those of skill in the art such that further explanation isnot required. In embodiments, the gate structure 100 includes spacers105 formed on a gate metal 110 and a capping material 115, e.g., nitridematerial.

As shown in FIG. 11, contact trenches 125 are formed in the interleveldielectric material 120, between the gate structures 100. Inembodiments, the contact trenches 125 are formed using lithography andetching processes. More specifically, a mask (photoresist) 18 is exposedto energy (light) to form a pattern masking the active region, e.g.,gate structures 100. The interlevel dielectric material 120 is thensubjected to an etching process, e.g., RIE, to remove portions of theinterlevel dielectric material 120. During this etching process, thegate structures 100, e.g., nitride, remain protected by the mask.

As shown in FIG. 12, a liner material 130 is deposited within thecontact trenches 125, followed by a metal material 135. The combinationof the liner material 130 and the metal material 135 will form contacts140. In embodiments, the metal material 135 can be, e.g., WSix; althoughother metal or metal alloys are contemplated by the present invention.In embodiments, the liner material 130 can be Ti or TiN or combinationsthereof. The metal material 135 and liner material 130 can be depositedusing conventional deposition processes, e.g., chemical vapor deposition(CVD) processes.

In FIG. 13, any residual metal material 135 and liner material 130 onthe interlevel dielectric material 120 can be removed using aconventional CMP process. Another insulator material 145, e.g., oxide,can be formed on the planarized surface, e.g., metal material 135, linermaterial 130, gate structure 100 and exposed portions of the interleveldielectric material 120. An opening 150 is formed in the insulatormaterial 145, partly exposing the contacts 140. The opening 150 isformed using conventional lithography and etching processes.

In FIG. 14, a metal material 155, e.g., WSix, is deposited in theopening 150 and in contact with the contacts 140. The metal material 155will also be deposited on the insulator material 145. An insulatormaterial 160 is deposited within the opening 150 and on the metalmaterial 155. In embodiments, the insulator material 160 can be nitrideor oxide; although other insulator materials are also contemplated bythe present invention. Any residual insulator material 160 formed on themetal material 155, outside the opening 150, can be removed by a CMPprocess, with the metal material 155 acting as an etch stop.

As shown in FIG. 15, contacts 165 are formed in direct electricalcontact with the contacts 140, through insulator material 170. Inembodiments, the contacts 165 are formed through the insulator material170, e.g., oxide, using conventional lithography, etching and depositionprocesses. For example, after deposition of the insulator material 170,a mask (photoresist) can be deposited on the insulator material 170 andexposed to energy to form a pattern. An etching process, e.g., RIE, canbe performed through the pattern to form an opening in the insulatormaterial 170 to expose the metal material of the contacts 140. A metalmaterial, e.g., tungsten, TiN, etc., can be deposited within the openingto form the contacts 165. Any residual material formed on the insulatormaterial 170 can then removed by a CMP process. In this way, contacts170 are formed off of the same plane of the fuse or resistor.

FIG. 16 shows an alternative structure and respective fabricationprocesses according to additional aspects of the present invention.Referring to FIG. 16, the structure 10′″ includes a post CMP structurehaving a gate structure 100 formed in an interlevel dielectric material120 (formed on an insulator material, e.g., STI or BOX) usingconventional lithography, etching and deposition methods as should beunderstood by those of skill in the art such that further explanation isnot required. In embodiments, the gate structure 100 includes spacers105 formed on a gate metal 110 and a capping material 115, e.g., nitridematerial.

As previously described, contacts 140 are formed in contact trenchesformed in the interlevel dielectric material 120, between the gatestructures 100. In embodiments, the contact trenches are formed usinglithography and etching processes as previously described. The contacts140 can include, e.g., a liner material and metal material depositedusing conventional deposition processes, e.g., CVD processes. Inembodiments, the metal material can be, e.g., WSix, and the linermaterial 130 can be Ti or TiN or combinations thereof. Any residualmetal material and liner material on the interlevel dielectric material120 can be removed using a conventional CMP process.

In comparison to FIG. 13, for example, a recess 200 is formed directlyin the interlevel dielectric material 120 between the contacts 140. Therecess 200 is formed using conventional lithography and etchingprocesses. A metal material 155, e.g., WSix, is deposited in the recess200 and in contact with the contacts 140. The metal material 155 willalso be deposited on the insulator material 145. An insulator material160 is deposited within the recess 200 and on the metal material 155. Inembodiments, the insulator material 160 can be nitride or oxide;although other insulator materials are also contemplated by the presentinvention. Any residual insulator material 160 and metal material 155formed outside the recess 200 can be removed by a CMP process stoppingon the insulator material 120 thus forming a dielectric cap with theinsulator material 160.

Still referring to FIG. 16, contacts 165 are formed in direct electricalcontact with the contacts 140, through insulator material 170. Inembodiments, the contacts 165 are formed through the insulator material170, e.g., oxide, using conventional lithography, etching and depositionprocesses. For example, after deposition of the insulator material 170,a mask (photoresist) can be deposited on the insulator material 170 andexposed to energy to form a pattern. An etching process, e.g., RIE, canthen be performed through the pattern to form an opening in theinsulator material 170 to expose the metal material of the contacts 140.A metal material, e.g., tungsten, TiN, etc., can then be depositedwithin the opening to form the contacts 165. Any residual materialformed on the insulator material 170 can then removed by a CMP process.In this way, contacts 170 are formed off of the same plane of the fuseor resistor.

In alternative aspects of the invention, a structure comprises: an efuseformed above the contacts and the replacement gate structures in adielectric material, the replacement gate metals including a nitridecapping material, the efuse is provided within a recess of thedielectric material, and the efuse comprises a nitride insulatormaterial and a metal material which is in contact with a contactstructure formed in an insulator material above the efuse. In anadditional aspects of the invention, a structure comprises: an efuseformed between contacts and the replacement gate structures in adielectric material, the replacement gate metals including a nitridecapping material, the efuse is provided within a recess of thedielectric material, and the efuse comprises a nitride insulatormaterial and a metal material which is in contact with a contactstructure formed in an insulator material above the efuse.

The method(s) as described above is used in the fabrication ofintegrated circuit chips. The resulting integrated circuit chips can bedistributed by the fabricator in raw wafer form (that is, as a singlewafer that has multiple unpackaged chips), as a bare die, or in apackaged form. In the latter case the chip is mounted in a single chippackage (such as a plastic carrier, with leads that are affixed to amotherboard or other higher level carrier) or in a multichip package(such as a ceramic carrier that has either or both surfaceinterconnections or buried interconnections). In any case the chip isthen integrated with other chips, discrete circuit elements, and/orother signal processing devices as part of either (a) an intermediateproduct, such as a motherboard, or (b) an end product. The end productcan be any product that includes integrated circuit chips, ranging fromtoys and other low-end applications to advanced computer products havinga display, a keyboard or other input device, and a central processor.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed:
 1. A method comprising: forming metal gates having acapping material on a top surface thereof; protecting the metal gatesand the capping material during an etching process which forms a recessin a dielectric material; forming an insulator material and metalmaterial within the recess; removing excess insulator material formed onthe metal material outside the recess; and forming a contact in directelectrical contact with the metal material.
 2. The method of claim 1,further comprising forming contact structures in the dielectric materialbetween the metal gates, wherein the recess is formed between thecontact structures and the recess is first filled with the metalmaterial followed by the insulator material.
 3. The method of claim 1,further comprising forming contact structures in the dielectric materialbetween the metal gates, wherein the recess is formed as an opening inthe dielectric material above the contact structures, and the opening isfirst filled with the metal material followed by the insulator.
 4. Themethod of claim 1, further comprising forming a pattern on the insulatormaterial prior to forming the contact.
 5. A method comprising: formingmetal gate structures in a dielectric material; forming a cappingmaterial over the metal gate structures; forming a mask over the cappingmaterial of the metal gate structures; recessing the dielectric materialbetween the metal gate structures by an etching process while the maskover the capping material protects the capping material and the metalgate structures; depositing insulator material and metal material withinthe recess in the dielectric material; removing excess insulatormaterial formed on the metal material outside the recess; and forming acontact in direct electrical contact with the metal material.
 6. Themethod of claim 5, wherein the metal gate structures are a plurality ofgate modules, and the forming of the recess includes etching thedielectric material and one of the gate modules.
 7. The method of claim6, further comprising: forming a second insulator material over themetal material; and planarizing the insulator material, metal materialand second insulator material, prior to forming of the contact, whereinthe insulator material, metal material and second insulator material aredeposited in a sequential order of the insulator material, metalmaterial and second insulator material.
 8. The method of claim 5,further comprising forming contact structures in an underlyingdielectric material between the metal gate structures, wherein therecess is formed between the contact structures and the recess is firstfilled with the metal material followed by the insulator material. 9.The method of claim 5, further comprising forming contact structures inan underlying dielectric material between the metal gate structures,wherein the recess is formed as an opening in the dielectric materialabove the contact structures, and the opening is first filled with themetal material followed by the insulator.
 10. The method of claim 5,wherein the insulator material and the metal material are planar withthe capping material.
 11. The method of claim 5, further comprisingforming a pattern on the insulator material prior to forming thecontact.